CGTalk - IK pops problem

mousework

08-31-2008, 07:18 AM

Dear Animators,

I wonder if anyone ever encounter this problem or maybe has a better way of doing it.

I was experimenting on jumping locomotion first in 2D then trace it in 3D. See links:

http://www.huberttalib.com/jumptests.html

You notice in the CG animation the Arm and even the legs pops slightly as it moves. Both have IK assigned to it. I trace and move pole constraint on each frames to prevent this, but it still does it.

Maybe someone out there knows some tricks or short cut working with pole constraint so it won't cause any IK pops.

Suggestions would be 1000 times appreciated.

Thanks,
Mousework

JayG

08-31-2008, 08:58 AM

IK pops are caused by the arm/leg extending farther than it should be allowed and then bending again over one frame. Most of the time even when it's completely straight but not overstretched it will still pop.

The best way to avoid them is try and avoid over-straightening your arms or legs, but in the end it's all about spacing. Use your keys to control how far the elbow or knee is bending so that it doesn't pop. =)

If you're referring to the elbow/knee moving around, again it's all about your keys. Good planning and blocking will prevent that from happening. With experience you'll nullify 98% of that before you even get into spline.

mousework

08-31-2008, 10:02 AM

Thanks for your quick reply JayG, this is great.

Yes what I meant was actually with the elbow/knee popping. What I did is actually. First I block up the arm and pole constraint. Then key all frame by frame from pose to pose.

I have just updated the example with some screen shot (Arm and pole constraint).

http://www.huberttalib.com/jumptests.html

My main question was actually. Do you key every frame, or just work from pose to pose.

I am new to this, and I just like to know more how professional animator (like you) do this. Do they animate every frame when animating arm/leg or do it pose to pose then work later on the curves.

I also want to say that you animation is very nice on your website. Looks very professional.. Very good work..:)

Thanks for your advise and much appreciated.

Cheers :).

JayG

08-31-2008, 05:25 PM

There are times when you have to go in and put in more keys to smooth out jiggles in the elbows, etc. but generally speaking you should be able to eliminate it with your regular keys if your motion is correct.

Keying every frame seems like it would work fine, (and does sometimes) but usually you'll still get some weird little jiggles in there even on 1's. It's all about the original keys and the motion of the arms. Try to plan it out so that the arms move in a way where the elbows won't do it. Tricky stuff, but yeah animation is hard :P Thanks for checkin' out the website too. Good luck man =)

mousework

08-31-2008, 10:22 PM

Thanks Jay,

This will definitely help on my next time blocking. cheers.

Just looking on you VanillaJump, this help me alot just looking frame per frame.

cheers :)

JayG

09-01-2008, 01:25 AM

Cool! That was a test I did trying to capture a subtle natural jump with no exaggeration on a light character. I don't remember having any trouble at all with the elbows jiggling around on that one, so it may help ya. One shot I remember it being a nightmare was on the Sticky Door I did. His arms were way over stretched so when they came back to normal the elbows bounced all over the place, what a pain in the neck! It was a good lesson though. =)

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